Draba incerta |
Draba asprella |
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whitlow-wort, Yellowstone Draba, Yellowstone Draba whitlow-wort, Yellowstone whitlow-grass, Yellowstone whitlow-wort |
rough Draba, rough whitlowgrass |
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Habit | Perennials; (cespitose, often pulvinate); caudex branched (dense with persistent leaf remains, branches sometimes terminating in sterile rosettes); scapose. | Perennials; (cespitose); caudex branched (with some persistent leaf bases); scapose. | ||||
Stems | unbranched, (0.2–)0.4–1.4(–2.1) dm, often pubescent throughout, sometimes glabrous distally, trichomes often simple and 2–5-rayed, 0.1–0.5 mm, (sometimes with mostly subpectinate ones). |
unbranched, (0.4–)0.6–1.5(–2.7) dm, pubescent throughout, trichomes simple, 0.5–1.5 mm, and 2–4-rayed ones, 0.05–0.3 mm, (sometimes 2–4-rayed ones distally). |
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Basal leaves | rosulate; petiolate; petiole (0–1 cm), ciliate throughout; blade narrowly oblanceolate to linear, (0.4–)0.6–1.7(–2.5) cm × (1–)1.5–3.5(–5) mm, margins entire, (ciliate, trichomes usually simple, rarely 2-rayed, 0.2–1.1 mm), surfaces usually pubescent with short-stalked, pectinate trichomes, 0.15–0.5 mm, sometimes also with 4–6-rayed ones, (midvein usually obscure abaxially), sometimes glabrous adaxially. |
rosulate; subsessile or shortly petiolate; petiole ciliate throughout; blade oblanceolate to spatulate or obovate, (0.6–)0.8–4.5(–6) cm × 2–12(–16) mm, margins usually entire, rarely obscurely dentate, (not ciliate), surfaces abaxially pubescent with stalked, (2–)4-rayed trichomes, 0.2–1 mm, adaxially with stalked, 2–4-rayed trichomes, 0.3–0.8 mm, and simple ones, 0.5–1.9 mm. |
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Cauline leaves | usually 0 (or 1, as a bract); sessile; blade linear to oblong, margins entire, surfaces pubescent as basal. |
0. |
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Racemes | 3–14(–30)-flowered, usually ebracteate, rarely proximalmost flowers bracteate, elongated in fruit; rachis not flexuous, glabrous or pubescent as stem. |
(15–)30–75-flowered, ebracteate, elongated in fruit; rachis not flexuous, pubescent, trichomes 2–4-rayed, sometimes with simple ones. |
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Flowers | sepals broadly ovate, 2.5–3.5(–4) mm, pubescent, (trichomes simple and 2- or 3-rayed); petals yellow (fading white), oblanceolate to obovate, 4–6 × 1.5–2.5 mm; anthers ovate, 0.3–0.5 mm. |
sepals broadly ovate, 1.8–3.5 mm, pubescent, (trichomes simple and short-stalked, 2–4-rayed); petals pale yellow, oblanceolate, 4–7 × 1.5–2.5 mm; anthers ovate to oblong, 0.4–0.7 mm. |
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Fruiting pedicels | ascending, straight, (2.5–)4–11(–27) mm, glabrous or pubescent, trichomes 2–5-rayed or pectinate. |
horizontal to divaricate-ascending, straight, 3–11(–16) mm, pubescent, trichomes 2–4-rayed, sometimes with simple ones. |
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Fruits | broadly ovate to lanceolate, plane, flattened, 5–9(–11) × 2–4 mm; valves glabrous or puberulent, trichomes simple and 2-rayed, 0.05–0.3 mm; ovules 8–16(–20) per ovary; style 0.2–0.9 mm. |
ovoid-ellipsoid to oblong, plane, inflated basally, 3–8 × 1.8–3.5 mm; valves hirsute, trichomes simple and spurred, (0.2–)0.3–1 mm, or puberulent, trichomes short-stalked, 2–4-rayed, 0.1–0.2 mm; ovules 8–12(–18) per ovary; style 0.6–2(–2.5) mm. |
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Seeds | oblong, 1.1–1.5 × 0.7–1 mm. |
oblong, 0.9–1.2 × 0.6–0.8 mm. |
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2n | = 112. |
= 30. |
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Draba incerta |
Draba asprella |
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Phenology | Flowering Jun–Aug. | |||||
Habitat | Rock outcrops, talus, gravelly areas, tundra | |||||
Elevation | 0-3300 m (0-10800 ft) | |||||
Distribution |
AK; CO; ID; MT; NV; UT; WA; WY; AB; BC; QC; YT
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AZ
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Discussion | Draba incerta was shown by G. A. Mulligan (1972) to be sexually reproducing and 14-ploid with x = 8. It is often confused with the apomict D. oligosperma (2n = 32, 64). Draba incerta is readily separated from D. oligosperma by having well-formed (versus abortive) anthers and pollen, stalked (versus sessile) leaf trichomes, and ciliate (versus non-ciliate) basal leaves with obscure (versus prominent) midveins. Although both species have leafless scapes, one often finds a bract adnate to, or subtending, the proximalmost pedicel in D. incerta. Draba incerta is found near sea level in Alaska. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Varieties 2 (2 in the flora). Both R. C. Rollins (1993) and N. H. Holmgren (2005b) indicated that the chromosome number of Draba asprella is 2n = 32, but repeated counts by one of us (M. D. Windham 2000, unpubl.) show that the species consistently has 2n = 30. Rollins divided D. asprella into four varieties encompassing tremendous variation in trichome morphology. One of these (var. zionensis) is more closely related to D. sobolifera (Windham and L. Allphin, unpubl.) and is treated herein at species rank. Within D. asprella, in the strict sense, we recognize two varieties separated primarily by the type of trichomes found on the fruits. The distinctions are not absolute and there appear to be forms connecting the two, especially in Coconino County. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 7, p. 313. | FNA vol. 7, p. 293. | ||||
Parent taxa | Brassicaceae > tribe Arabideae > Draba | Brassicaceae > tribe Arabideae > Draba | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | D. exalata, D. incerta var. laevicapsula, D. incerta var. peasei, D. laevicapsula, D. peasei | |||||
Name authority | Payson: Amer. J. Bot. 4: 261. (1917) | Greene: Bull. Torrey Bot. Club 10: 125. (1883) | ||||
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